This invention relates to sharpening the spatial resolution of multispectral imagery.
This invention relates particularly to methods and apparatus of combining registered high spatial resolution panchromatic imagery and lower spatial resolution multispectral imagery to synthesize higher spatial resolution multispectral imagery.
When collecting images on the Earth for mapping purposes, there are practical and economic benefits if high resolution multispectral (color) imagery can be generated with lower resolution sensors. Less expensive products can be used and smaller transmission bandwidths from the satellites can be used, if lower resolution multispectral imagery can be synthesized to higher spatial resolution multispectral imagery.
It is known, in general, that registered high spatial resolution panchromatic imagery can be combined with lower spatial resolution multispectral imagery to synthesize higher resolution multispectral imagery. But obtaining satisfactory results can be a problem using various prior art techniques.
The degree of misregistration between bands and the correlation of intensity values are key factors in generating radiometrically accurate and visually crisp output images.
When the collected registered panchromatic data is registered (spectrally and spatially) so that the panchromatic data both covers the spectral range of sensitivity of each of the multispectral bands and also covers the same physical image location on the Earth, it is possible to generate high resolution multispectral imagery with lower resolution multispectral sensors using the methods and apparatus of the present invention.
The methods and apparatus of the present invention weigh the intensity values of the multispectral imagery according to how the colors (multispectral imagery) act relative to the panchromatic imagery, rather than how a single color acts relative to the panchromatic imagery.
The methods and apparatus of the present invention use all the colors for each of the sharpening steps.
The present invention creates an ensemble to sharpen just the right color. The present invention uses color intensity as it applies to the over all image and also uses color intensity as it applies to a particular sub-pixel in the over all image.
The present invention provides a model for how the color intensities are related to the panchromatic intensities as a complete set, and the model functions as an ensemble rather than as individual colors.
In the present invention a particular color band is not really head-to-head correlated; but, as part of a group, it becomes better correlated in accordance with the present invention.
The present invention also can tolerate more misregistration than the correlation methods and apparatus used prior to the present invention.